Ecological insights from plant and animal assemblages from a Late Bronze/Early Iron Age channel stratigraphy in the Kyzylkum Desert of Uzbekistan.

The Kyzylkum Desert of Uzbekistan preserves former branches of the Zerafshan River that once supported settlements such as the Late Bronze/Early Iron Age site of Kimirek-kum 1 (KK1). Here we reconstruct past ecosystems surrounding KK1 through multiproxy analysis of a stratified channel deposit, Trench H-2, that formed part of the site’s circular enclosure. The sequence was investigated using 14C and OSL dating, sediment composition and grain-size analyses, and pollen, phytolith, macrobotanical, ostracod, and faunal data, supported by field observations of the local palaeochannel system. A Bayesian age–depth model constrains deposition within the channel to between ca. 1230 and 1030 ± 40 cal yrs BCE, contemporaneous with activity at KK1. During the earlier part of this interval (ca. 1230–1115 ± 40 cal yrs BCE), botanical proxies document a Tugai riparian forest of poplar, tamarisk, elm, alder, and reed sustained by local branches of the Zerafshan River. Ostracod assemblages indicate shallow freshwater conditions with abundant aquatic plants. Inhabitants of KK1 exploited local wood biomass as firewood, and practiced animal husbandry and crop cultivation. Around 1120–1110 ± 40 cal yrs BCE, a pronounced and rapid shift in plant assemblages, from woody riparian taxa to salt-tolerant shrubs and herbs, records a process of halophytization likely driven by altered river hydrology and declining groundwater. The ecological transition recorded in Trench H-2 corresponds to a phase of cooler and progressively more arid climatic conditions documented in regional palaeoclimatic records, suggesting that broad climatic forcing shaped local hydrologies and ecological response.